Transcription Termination Factor Rho



Transcription termination factor Rho is a ring-shaped RNA-DNA helicase that induces release of transcription complexes at specific loci of bacterial genomes. Several structures of Rho in various liganded states haven been solved by X-ray crystallography by the J. M. Berger lab (Berkeley): 1a8v, 1pv4, 1pvo, 1xpr, 1xpu, 2a8v, and 2ht1.

The asymmetric unit solved as 2ht1 contains only two chains, so it represents only one third of the biological unit, which is a homo-hexamer. The scene here shows this homo-hexamer in a closed state (restore initial scene ). Note that this model has only the middle 324 amino acids in each chain, lacking the first 52 and the last 57 amino acids in each chain.

In this model (show composition ), the hexamer is bound to, and some incidental "" (sulfate ions).

Here is one representation showing the same Rho hexamer in a closed state and with RNA fragments occupying both its primary and secondary binding sites. In this scene, the foreground RNA is colored by element (

). Also colored are Lys181, Lys283 , Arg347 , Arg353 , and (in black) background RNA.

Additional Resources
For additional information, see: Transcription and RNA Processing